2008components of sex-differential expression were determined, but regulation by the sex-determination hierarchy was not explored.Here, we identify genes that are expressed sex-differentially in somatic tissues of adults and regulated by the sex hierarchy. Using arrays that assay approximately one-third (4040) of Drosophila genes, we analyzed adults mutant for the regulatory genes transformer (tra), dsx and fru (Fig. 1). To select a small number of such genes for further study, we chose a conservative approach. Stringent statistical analysis of these data, combined with data from wild-type adults and adults that lack germline tissue (Arbeitman et al., 2002), identified 63 genes that are sex-differentially expressed in the adult soma and regulated by the somatic sex hierarchy. Additional selection criteria, and validation by RNA blot analysis, defined a set of 11 genes for further characterization. In situ hybridization revealed that sex-differential expression of all 11 genes is confined to the internal genitalia. Analysis of the regulation of these genes revealed that the sex hierarchy functions during development to specify their adult expression patterns, and that dsx probably functions in diverse ways to set their activities.
Materials and methods
Drosophila stocks
Microarray experimentsMicroarray production, data acquisition and analysis were performed as described in (Arbeitman et al., 2002). Each hybridization was a comparison of one RNA sample to a reference sample that was comprised of RNA derived from whole animals representing all stages of the life-cycle. Normalization was calculated so that the average ratio of signals from the experimental and reference sample equalled one. Analyses were performed on log-transformed ratio values. In all cases, chromosomal males and females were sampled separately. The wild-type data set and tudor data set were described previously (Arbeitman et al., 2002); each time point was sampled in duplicate. The wild-type data set includes 0-to 24-hour-, 3-day-, 5-day-, 10-day-, 15-day-, 20-day-, 25-day-and 30-day-old adults. The tudor data set includes 0-to 24-hour-and 5-day-old adults. Microarray experiments on sex determination mutants tra 1 /Df(3L)stj7 (XX), fru 4-40 /fru p1 (XY) and Dsx D /dsx m+r15 (XX) were performed with four (tra and fru) or five (Dsx D ) replicates. Microarray experiments performed on dsx null mutants (dsx m+r15 /dsx d+r3 ) were sampled in duplicate.